28128 Parallax Inc, 28128 Datasheet - Page 99

• Manufacturer Part Number: 28128
• Description: KIT BASIC ANALOG/DIGI PARTS ONLY
• Manufacturer: Parallax Inc

Specifications of 28128

• Accessory Type: ADC, DAC
• Product: Microcontroller Accessories
• For Use With/related Products: BASIC Stamp® 2 and Board of Education
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Chapter 5: Time Varying Signals · Page 89
Chapter #5: Time Varying Signals
In this chapter we'll view signals with the Stamp-O-Scope. To do this we'll use the
BASIC Stamp along with the A/D and D/A circuits built in Chapters #3 and #4 to
emulate the function of an oscilloscope.
The voltage output of the resistive ladder network will be varied with time, and the
changes will be tracked using our oscilloscope emulator, the Stamp-O-Scope. The
Stamp-O-Scope will gather its input voltage data from the ADC0831 and display it
graphically in the Debug Terminal.
We'll view two different signals using the Stamp-O-Scope, and we'll use the D/A
converter to adjust the attributes of both signals. The first signal we'll work with is called
a triangle wave, and the second is called a pulse train. The LED will be used to monitor
the activity of both signals.
Unlike a normal oscilloscope, the Stamp-O-Scope cannot monitor voltage signals at
frequencies in the audible sound range. However, the BASIC Stamp can easily send a
voltage signal in the audible sound range via the D/A converter. This signal can be used
to make a speaker emit tones of adjustable pitch and volume.
The pitch and volume will be adjusted by changing two of the pulse train's properties.
But first, let's get started and view these properties with the Stamp-O-Scope.
Also in this experiment, the BASIC Stamp is used to generate sine waves (see Figure 5-1)
of adjustable frequency. These sine waves are used to make musical notes.